Co-Cured UV/Visible Light-Resistant Coated Composite Material for Aircraft Wing Fuel Tank Assembly

ABSTRACT

Composite material protection from UV degradation is disclosed by providing a co-cured composite material substrate co-cured with a UV/visible light-resistant layer to form co-cured composite materials for exclusively imparting UV/visible light-resistant properties to co-cured composite material substrates for use in UV/visible light-resistant vehicle fuel tank assemblies.

CROSS-REFERENCE

This U.S. Non-Provisional Patent Application is a Continuation-in-Partof USSN 17/708,207 filed Mar. 30, 2022, the entire contents of which areincorporated by reference herein.

TECHNOLOGICAL FIELD

The present disclosure relates generally to the field of compositematerials, and composite materials used for manufacturing largestructural components. More specifically, the present disclosure relatesto the field of composite materials used for structural materials forinterior and exterior surfaces of large structural aircraft components.

BACKGROUND

The use of composite materials in the manufacture of various structuralcomponent parts continues to increase. At least due to thestrength-to-weight ratios, composite materials offer advantages asreplacements for denser materials, such as, for example, metals, metalalloys, etc., where the overall weight of a completed structure (or theweight of a component part of a completed structure) is an importantconsideration in the selection of materials used in the manufacture ofsuch a completed structure, or in the manufacture of a component of acompleted structure.

Coating layers applied to composite materials are not as durable as, orhave the longevity of, the composite materials to which such coatinglayers are applied. Composite material assemblies may otherwise compriseexternal or internal layers that can include, for example, protectivecoatings or other coating layers. For example, when composite materialsare used in the fabrication of vehicles including, for example,aircraft, exterior paint coatings, referred to as an aircraft “livery”,may require alteration, rework, change of logo, design, color scheme,etc., over the useful life of the vehicle. Such livery alteration, forexample, may include the removal of one or more decorative coatinglayers applied onto a composite material, including, for example, one ormore paint layers. However, the removal of one layer or layer type(paint, primer, adhesion promoting layer, adhesive layer, etc.) frommaterials stacked onto a composite material can require the removal ofadditional layers or layer types that then must be built back up, orotherwise reconstituted. In addition, livery alteration requiring paintremoval via use of paint removal techniques can damage underlyinglayers, or even damage composite materials, if the composite materialsare exposed to excessive mechanical paint removal techniques.

Unless explicitly identified as such, no statement herein is admitted asprior art merely by its inclusion in the Technological Field and/orBackground section.

SUMMARY

According to present aspects, a co-curable composite material isdisclosed, with the co-curable composite material comprising aco-curable composite structural material substrate and a co-curableUV/visible light-resistant coating layer, with the co-curable UV/visiblelight-resistant coating layer comprising at least one of fiberglassfibers, carbon fibers, polyester fibers, aramid fibers, boron fibers,quartz, and combinations thereof, with the co-curable UV/visiblelight-resistant coating layer in direct contact with the co-curablecomposite structural material substrate to form a co-curable/co-curedUV/visible light-resistant layer-coated composite material substrate,that can, for example, significantly impact composite materialmanufacture and improve the performance and reduce the weight of thecomposite structural material substrate by at least obviating the needto include separate UV/visible light-resistant coatings formerly appliedto composite structural material substrates, such as, in the preparationof a composite material system used in structural assemblies for largercomponents, including internal and exterior surfaces of vehicles,including, for example, vehicles such as aircraft, and further includingvehicle fuel tanks (e.g., aircraft fuel tanks) that can be located, forexample, within an aircraft wing assembly.

According to present aspects, in the co-cured state, the co-curedUV/visible light-resistant layer-coated composite material substrate canbe further configured to form a vehicle fuel tank. The vehicle fuel tankcomprises a vehicle fuel tank inner surface, and a vehicle fuel tankcavity, with the vehicle fuel tank cavity defined by and otherwisesurrounded by the vehicle fuel tank inner surface with the vehicle fueltank inner surface exclusively comprising the co-curable UV/visiblelight-resistant coating layer, with the co-curable UV/visiblelight-resistant coating layer comprising at least one of fiberglassfibers, carbon fibers, polyester fibers, aramid fibers, boron fibers,quartz, and combinations thereof, wherein the co-curable UV/visiblelight-resistant coating layer has a UV/visible light transmittance valueof 0% to about 20% for UV/visible wavelengths ranging from about 200 nmto about 800 nm when the co-curable UV/visible light-resistant coatinglayer comprises an average thickness ranging from about 2 mils to about6 mils, and wherein said co-curable UV/visible light-resistant coatinglayer is configured to completely cover said co-curable compositematerial substrate.

In another aspect, said co-curable UV/visible light-resistant coatinglayer comprises fiberglass fibers.

In another aspect, the co-curable composite material substrate isco-curable with the co-curable UV/visible light-resistant coating layerat a temperature ranging from about 250° F. to about 410° F.

In another aspect, the co-curable composite material substrate comprisesan epoxy resin-based matrix.

In a further aspect, the co-curable composite material substratecomprises a fiber reinforced epoxy resin-based matrix comprising atleast one of carbon fibers, boron fibers, aramid fibers, fiberglassfibers, polyester fibers, and combinations thereof.

In another aspect, the co-curable composite material substrate comprisesa carbon fiber reinforced polymer composite material.

In another aspect, the co-curable composite material substrate comprisesat least one carbon fiber reinforced polymer prepreg.

According to another present aspect, a vehicle fuel tank is disclosed,with the vehicle fuel tank comprising a vehicle fuel tank assemblycomprising a co-cured composite material, with the vehicle fuel tankassembly comprising a vehicle fuel tank inner surface. The vehicle fueltank inner surface comprises a co-cured composite material substrate, aco-cured UV/visible light-resistant coating layer, with the co-curedUV/visible light-resistant coating layer comprising at least one offiberglass fibers, carbon fibers, polyester fibers, aramid fibers, boronfibers, quartz, and combinations thereof, with the co-cured UV/visiblelight-resistant coating layer in direct contact with the co-curedcomposite material substrate, with the co-cured UV/visiblelight-resistant layer configured to completely cover the co-curedcomposite material substrate. The vehicle fuel tank further comprises avehicle fuel tank cavity, with the vehicle fuel tank cavity defined bythe vehicle fuel tank cavity inner surface. The co-cured compositematerial substrate and the co-cured UV-resistant coating layer areco-cured in a co-curing regimen to form the vehicle fuel tank assembly,said co-curing regimen comprising a co-curing temperature ranging fromabout 250° F. to about 410° F., and the co-cured UV/visiblelight-resistant layer has a UV/visible light transmittance value of 0%to about 20% for UV/visible wavelengths ranging from about 200 nm toabout 800 nm when the co-curable and co-cured UV/visible light-resistantcoating layer comprises an average thickness ranging from about 2 milsto about 6 mils.

In another aspect, said co-cured UV/visible light-resistant coatinglayer comprises fiberglass fibers.

In another aspect, the co-cured composite material substrate comprisesan epoxy resin-based matrix.

In another aspect, the co-cured composite material substrate comprises afiber reinforced epoxy resin-based matrix comprising at least one ofcarbon fibers, boron fibers, aramid fibers, fiberglass fibers, polyesterfibers, and combinations thereof.

In a further aspect, the co-cured composite material substrate comprisesa carbon fiber reinforced polymer composite material.

In another aspect, the co-cured composite material substrate comprisesat least one carbon fiber reinforced polymer prepreg.

In a further aspect, the co-cured UV/visible light-resistant coatinglayer is configured to form the vehicle fuel tank cavity inner surface.

In a further aspect, the vehicle fuel tank inner surface furthercomprises a fuel tank primer layer disposed to cover the co-curedUV/visible light-resistant layer, said fuel tank cavity inner surfacedefined by the fuel tank primer layer.

In another aspect, inclusion of the said co-cured UV/visiblelight-resistant layer in the co-cured composite material assemblyobviates the presence of at least one of a fuel tank primer layer and aUV-absorbing paint layer in the vehicle fuel tank assembly.

A further present aspect discloses an aircraft wing assembly comprisinga vehicle fuel tank comprising a vehicle fuel tank assembly comprising aco-cured composite material, with the vehicle fuel tank assemblycomprising a vehicle fuel tank inner surface. The vehicle fuel tankinner surface comprises a co-cured composite material substrate, aco-cured UV/visible light-resistant coating layer, with the co-curableUV/visible light-resistant coating layer comprising at least one offiberglass fibers, carbon fibers, polyester fibers, aramid fibers, boronfibers, quartz, and combinations thereof, with the co-cured UV/visiblelight-resistant coating layer in direct contact with the co-curedcomposite material substrate, said co-cured UV/visible light-resistantcoating layer configured to completely cover the co-cured compositematerial substrate. The vehicle fuel tank further comprises a vehiclefuel tank cavity, with the vehicle fuel tank cavity defined by thevehicle fuel tank cavity inner surface. The co-cured composite materialsubstrate and the co-cured UV/visible light-resistant coating layer areco-cured in a co-curing regimen to form the vehicle fuel tank assembly,with the co-curing regimen comprising a co-curing temperature rangingfrom about 250° F. to about 410° F., and the co-cured UV/visiblelight-resistant layer has a UV/visible light transmittance value of 0%to about 20% for UV/visible light wavelengths ranging from about 200 nmto about 800 nm when the co-cured UV/visible light-resistant layercomprises an average thickness ranging from about 2 mils to about 6mils.

In another aspect, a vehicle comprises a vehicle fuel tank comprising avehicle fuel tank assembly comprising a co-cured composite material,with the vehicle fuel tank assembly comprising a vehicle fuel tank innersurface. The vehicle fuel tank inner surface comprises a co-curedcomposite material substrate, a co-cured UV/visible light-resistantlayer, with the co-cured UV/visible light-resistant coating layercomprising at least one of fiberglass fibers, carbon fibers, polyesterfibers, aramid fibers, boron fibers, quartz, and combinations thereof,with the co-cured UV/visible light-resistant layer in direct contactwith the co-cured composite material substrate, with the co-curedUV/visible light-resistant layer configured to completely cover theco-cured composite material substrate. The vehicle fuel tank furthercomprises a vehicle fuel tank cavity, with the vehicle fuel tank cavitydefined by the vehicle fuel tank cavity inner surface. The co-curedcomposite material substrate and the co-cured UV/visible light-resistantlayer are co-cured in a co-curing regimen to form the vehicle fuel tankassembly, said co-curing regimen comprising a co-curing temperatureranging from about 250° F. to about 410° F., and the co-cured UV/visiblelight-resistant layer has a UV/visible light transmittance value of 0%to about 20% for UV/visible wavelengths ranging from about 200 nm toabout 800 nm when the UV/visible light-resistant layer comprises anaverage thickness ranging from about 2 mils to about 6 mils, with thevehicle selected from the group consisting of a crewed aircraft, anuncrewed aircraft, a crewed spacecraft, an uncrewed spacecraft, a crewedrotorcraft, an uncrewed rotorcraft, a crewed terrestrial vehicle, anuncrewed terrestrial vehicle; a crewed surface water borne vehicle, anuncrewed waterborne vehicle, a crewed sub-surface water borne vehicle,an uncrewed sub-surface water borne vehicle, a satellite, andcombinations thereof.

According to further present aspects, a method is disclosed, with themethod comprising providing a co-curable composite material substrate,said composite material substrate comprising a co-curable compositematerial substrate first side and a co-curable composite materialsubstrate second side. The method further comprises applying aco-curable UV/visible light-resistant layer onto said co-curablecomposite material substrate second side, with the co-curable UV/visiblelight-resistant coating layer comprising at least one of fiberglassfibers, carbon fibers, polyester fibers, aramid fibers, boron fibers,quartz, and combinations thereof, with the co-curable UV/visiblelight-resistant layer applied onto the composite material substratesecond side at an average thickness ranging from about 2 mils to about 6mils and co-curing the co-curable composite material substrate with theco-curable UV/visible light-resistant layer to form a co-cured compositematerial vehicle fuel tank assembly, with the co-cured compositematerial vehicle fuel tank assembly comprising a co-cured vehicle fueltank assembly inner surface, and with the co-cured composite materialvehicle fuel tank assembly inner surface comprising a co-curedUV/visible light-resistant layer having a UV/visible light transmittancevalue of 0% to about 20% for UV/visible wavelengths ranging from about200 nm to about 800 nm when the co-cured UV/visible light-resistantlayer comprises an average thickness ranging from about 2 mils to about6 mils, and with the co-cured UV/visible light-resistant layerconfigured to define a vehicle fuel tank cavity. According to thedisclosed methods, including the co-cured UV/visible light-resistantlayer in the co-cured composite material vehicle fuel tank assemblyobviates the need for the presence of at least one of a UV/visiblelight-absorbing detail primer layer and a UV/visible light-absorbingpaint layer in the co-cured composite material vehicle fuel tankassembly.

In another aspect, the co-cured composite material substrate comprises afiber reinforced epoxy resin-based matrix comprising at least one ofcarbon fibers, boron fibers, aramid fibers, fiberglass fibers, polyesterfibers, and combinations thereof.

In a further aspect, the co-cured composite material substrate comprisesa carbon fiber reinforced polymer composite material.

In another aspect, the method further comprises depositing a fuel tankprimer layer on the UV/visible light-resistant layer.

The features, functions and advantages that have been discussed can beachieved independently in various aspects or may be combined in yetother aspects, further details of which can be seen with reference tothe following description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described variations of the disclosure in general terms,reference will now be made to the accompanying drawings, which are notnecessarily drawn to scale, and wherein:

FIG. 1A is an illustration of a vehicle in the form of an aircraft,according to present aspects;

FIG. 1B is a cross-sectional side view of a vehicle fuel tank in theform of an aircraft wing assembly fuel tank;

FIG. 2A is an enlarged cross-sectional representative side view of aUV/visible light-resistant co-curable composite material, according topresent aspects;

FIG. 2B is an enlarged cross-sectional representative side view of aUV/visible light-resistant cured composite material, according topresent aspects;

FIG. 2C is an enlarged cross-sectional representative side view of aUV/visible light-resistant cured composite material system, according topresent aspects;

FIG. 3 is a flowchart outlining a method, according to present aspects;and

FIG. 4 is a flowchart outlining a method, according to present aspects.

DETAILED DESCRIPTION

Material layers that can be applied as, for example, coatings can beadded to a composite material surface for the purpose of changing thesurface characteristics of a composite material. For example, primers orother coating layers can be added to a composite material to improveadhesion of subsequent coating layers such as, for example, paints,topcoats, etc., to a composite material surface that may already haveone or more other coatings applied. The layering of coating materialsonto composite material surfaces is labor intensive, time-consuming andcan add substantial weight to large objects and large structures thatinclude such composite materials having multiple coating layers.

In addition, paint removal processes that remove various paint coatinglayers from composite materials often damage protective surfacing layersapplied to composite materials and that are applied beneath paintcoating layers can require significant resurfacing once the paint layersare stripped from the surfacing layers. For example, one or more of thecomposite material coating layers can each require separate surfacingpreparation steps and procedures prior to the subsequent deposition ofone or more coating layers onto composite material surfaces. In someinstances, a portion of one or more previously deposited coating must beremoved, or otherwise reworked, before adding further coating layers.Such intermediate reworking of composite material surfaces during thetreatment of composite material surfaces is also labor-intensive,time-consuming, and costly.

During the fabrication of composite material parts that can include forexample, an epoxy resin-based composite material, a carbon fiberreinforced polymer material, etc., composite material surfaces can beginto degrade at the composite material surface due to exposure to ambientultraviolet/visible light (UV/visible light) radiation. To avoid achange in outer surface characteristic of a composite material outersurface that can be caused, at least in part, by composite materialexposure to UV/visible light radiation, composite material surfaces areoften coated with at least one protective layer such as, for example, aspray applied surfacer, a primer layer, etc., with the protective layercontaining, for example, a UV “blocking” agent.

Such UV blocking agent layers are not typically disposed on assemblyinner surfaces where an inner mold line may define the compositematerial inner surface profile. Since UV/visible light degradation ofcomposite materials can also occur on an inner surface of a compositematerial substrate assembly (e.g., where an inner mold line, or IML canreside), present aspects contemplate treating such “inner” surfaces ofcomposite material assemblies such as, for example, vehicle fuel tankcavities housed within a vehicle fuel tank.

Applying UV mitigation, or “blocking” agents in layers to compositesurfaces often adds manufacturing complexity in the form of, at least,increasing manufacturing time, increasing rework time, increasingoverall production cost, etc., as such applied UV-blocking materialcoverings typically are removed from the composite material orreactivated chemically or mechanically before additional compositematerial assembly processing is conducted. In addition, primer andsurfacing film layers are often treated to accommodate a subsequentpaint layer or topcoat. This treatment of individual subsequent layersadded to a composite material system (that can be a composite materiallayered “stack”) again leads to increased manufacturing time, increasedrework time, increased overall production cost, etc.

Composite materials are typically post-processed or “reworked”, forexample, to repaint and/or resurface composite materials. For example,primers and paint coatings that include a UV mitigation, or a UV“blocking” agent can be applied to a composite material surface for thepurpose of protecting a composite material surface from degradationand/or discoloration that can be caused, for example, by exposing thecomposite material to UV/visible light radiation during the use of thecomposite material as a construction material in the manufacture of, forexample, a larger structure.

In addition, UV/visible light damage from UV/visible light wavelengthsimpacting coating layers used to coat composite materials and/orimpacting underlying composite materials during aircraft manufacture andaircraft use can cause a composite material to require material rework.Exposure to UV/visible light radiation can alter a material’scharacteristic over time. For example, UV/visible light radiation canrender a coating layer or composite material vulnerable to processingdamage, such as, for example, when a layer or composite material isexposed to, for example, a mechanical paint removal technique. Materiallayer selection for large structures to guard against environmentaldamage, including UV/visible light damage, can result in a requiredapplication of a series of coating layers, with each such coating layerapplication resulting in a significant amount of time, expense, andresulting added weight to large structures including, for example,aircraft (where weight considerations can further impact fuel usage,cargo and passenger capacity, aircraft range, etc.).

Present aspects are disclosed that are directed to co-curable andco-cured composite materials comprising a co-curable or co-cured layerof UV/visible light-resistant layer immediately contacting the compositematerial substrate. The co-curable or co-cured UV/visiblelight-resistant coating layer comprises at least one of fiberglassfibers, carbon fibers, polyester fibers, aramid fibers, boron fibers,quartz, and combinations thereof, The incorporation into the compositematerial substrate of the co-cured and co-curable UV/visiblelight-resistant layer significantly impacts composite materialmanufacture and improves the performance and reduces the weight of thestructural composite material by at least obviating the need to includeseparate UV-resistant coatings formerly applied to composite materialsubstrates, such as for the protection of composite materials fromUV/visible light damage, and for example, in the preparation of acomposite material system used in structural assemblies for largercomponents, including internal and exterior surfaces of vehicles,including, for example, aircraft.

According to present aspects, methods for improving the UV/visible lightprotection and reducing UV/visible light degradation of compositematerial substrate surfaces are presently disclosed, as well ascomposite material substrates having improved UV/visible lightprotection without the previously required presence of typically appliedprotective coverings or layers of UV/visible light-resistant primers orseparate layers of, for example, UV-absorbing paint(s). In addition topreventing UV/visible light degradation of underlying composite materialsubstrate surfaces, presently disclosed methods, systems, andapparatuses eliminate the need for protective coverings, protectiveprimer layers, UV-absorbing paint layers, with the result being areduction in a composite material system complexity and overallcomposite material layered stack weight that further reduces compositematerial processing time. The reduction in composite material UV/visiblelight degradation further decreases the occurrence of the need forcomposite material rework (required by such UV/visible lightdegradation).

FIG. 1A is an illustration of a vehicle in the form of an aircraft,according to present aspects. As shown in FIG. 1 , aircraft 10 includeswing assemblies 12, horizontal stabilizer assemblies 14, and verticalstabilizer assembly 16 with the presently disclosed composite materialsconfigured to form and otherwise be configured to form various aircraftassemblies including those shown in FIG. 1A. As further shown in FIG. 1Aaircraft wing assemblies 12 comprise vehicle fuel tanks in the form ofaircraft fuel tanks within the wing assemblies (referred to herein asaircraft wing assembly fuel tanks), with FIG. 1B showing across-sectional side view into wing assembly 13 along line 1B-1B. Asshown in FIG. 1B, aircraft wing assembly fuel tank 13 comprises a wingassembly fuel tank outer surface 13 a and a wing assembly fuel tankinner surface 13 b. FIG. 1B further shows a wing assembly fuel tankcavity 13 d, with the wing assembly fuel tank cavity 13 d defined by(e.g. surrounded by, bounded by) the aircraft wing assembly fuel tankinner surface 13 b.

According to present aspects a composite material substrate is providedthat can comprise an epoxy resin-based composite material in combinationwith a fiber in a matrix that can include carbon fibers, boron, fibers,aramid fibers, fiberglass fibers, polyester fibers, and combinationsthereof, with carbon fibers being particularly preferred, and with acarbon fiber reinforced polymer composite material being particularlypreferred as a composite material substrate.

According to further presently disclosed aspects, a composite materialfor use in the manufacture of a composite material structure furtherincludes a co-curable UV/visible light-resistant layer (equivalentlyreferred to herein as a UV/visible light-inhibiting layer) with theUV/visible light-resistant layer provided to the composite materialexclusively in the form of a co-curable UV/visible light-resistant layerthat can be, for example, a single co-curable UV/visible light-resistantlayer ply (for example, in the form of a single ply film layer) as theco-curable UV/visible light-resistant layer. According to furtherpresent aspects, the co-curable UV/visible light-resistant coating layercomprises at least one of fiberglass fibers, carbon fibers, polyesterfibers, aramid fibers, boron fibers, quartz, and combinations thereof.According to further present aspects, the co-curable UV/visiblelight-resistant layer is provided in intimate contact with theco-curable composite material substrate material, with the compositematerial substrate being co-curable with the co-curable UV/visiblelight-resistant layer to form a co-cured UV/visible light-resistantcoated composite material substrate.

According to present aspects, a “co-curable” material is defined as amaterial that can be co-cured with another material such that the twoco-curable materials will co-cure when exposed to common curingconditions, such as those that can be imposed by a predetermined curingregimen (predetermined temperature, pressure, ramp uptemperatures/rates, dwell periods, etc.) to form a “co-cured”composition.

The composite material substrate, also referred to equivalently hereinas the “base layer”, or the “underlayer”, or the “composite materialsubstrate layer” can be a co-curable composite material that can be anepoxy resin-based material, and that can include fiber reinforcedpolymer composite materials that can have an epoxy resin-based matrix,and that can include carbon fiber reinforced polymer compositematerials. In present aspects, the co-curable composite material can beany suitable composite material that can be co-cured with a co-curablelayer material at a co-curing temperature ranging from about 250° F. toabout 410° F.

Composite materials are often layered into laminates that have aselected number of composite material layers, often called “prepregs”.Prepregs can be “pre-impregnated” composite fibers where a matrixmaterial, such as an epoxy resin-based material, is already present. Thefibers often take the form of a weave, and the matrix is used to bondthem together and to other components during manufacture. The compositematrix material is typically partially cured to allow easy handling.Such composite matrix material may require cooled or cold storage toprevent further partial curing, or complete curing, and such compositematrix material is referred to as B-Stage material. Consequently,B-Stage prepregs are stored in cooled or cold storage areas, as ambientheat can accelerate complete polymerization. Prepregs also allow one toimpregnate a bulk amount of fiber and then store the prepreg in a cooledor cold storage area for an extended time until a later cure. Prepregspleas may be applied to tools which are flat or contoured depending uponthe fabrication process used. Multiple layers of prepreg plies are usedto make a desired shape using shaping or forming tools, also calledmandrels. Present aspects contemplate, but are not limited to, the useof laid up layers of composite material prepregs to form the co-curableand co-cured composite material substrate.

According to present aspects, a selected degree of UV/visiblelight-resistance and UV/visible light-protection can be exclusivelyimparted to the co-cured composite material substrate by immediatelycontacting a co-curable composite material substrate surface with aco-curable UV/visible light-resistant layer that, after co-curing thetwo materials, forms a co-cured UV/visible light-resistant coatedcomposite material. That is, according to present aspects, previouslyrequired UV/visible light-resistant primers, UV-blocking paints, etc.,can be eliminated and their presence is otherwise obviated as the UVprotection function within a UV/visible light-resistant compositematerial is exclusively satisfied by the addition and placement of aco-curable UV/visible light-resistant layer that is provided inimmediate contact with the co-curable composite material substrate.

According to present aspects, by co-curing the co-curable UV/visiblelight-resistant layer with the co-curable composite material, advantages(including UV-protection) are exclusively imparted by the presentlydisclosed co-cured UV/visible light-resistant layer at least to theunderlying co-cured composite material substrate that can be a co-curedepoxy-based composite material and can further be a co-cured carbonfiber reinforced polymer substrate material substrate. No furtherUV-protective layers (e.g., in the form of UV/visible light-resistantprimers, UV/visible light-resistant paints, etc.) are contemplated orare otherwise required to be included in the co-cured compositematerials of the present disclosure to impart a selected degree ofcomplete UV protection to the presently disclosed co-cured UV/visiblelight-resistant layer-coated composite materials. According to presentaspects, such imparted advantages include, without limitation, theUV/visible light protection of the “underlying” composite materialsubstrate (that can be an epoxy resin-based composite material), and theprotection of composite material substrate from deleterious effects ofmechanical paint removal techniques, etc.

In addition, the robustness of the presently disclosed co-curableUV/visible light-resistant layer that is co-cured onto, for example, aco-curable composite material substrate that can be an epoxy-basedcomposite material substrate can endure subsequent and repeated heattreatments that may be required during subsequent and repeatedrepainting protocols. That is, unlike some currently required repaintingprotocols, the presently described co-cured UV/visible light-resistantlayer need not be replaced, removed, or otherwise reapplied duringreworking, paint stripping, repainting, repeated heat treatments, etc.Accordingly, present aspects further contemplate the removal orreconditioning of only the layers coated atop the present co-curedUV/visible light-resistant layer (e.g., topcoat layers, basecoat layers,clearcoat layers, intermediate coating layers, etc.). In this way,present aspects disclose the protection of the composite material fromthe deleterious effect that would otherwise occur when a compositematerial surface is exposed to UV/visible light radiation.

Through the use of the presently disclosed co-cured UV/visiblelight-resistant coated composite material substrate, a significantnumber of procedural steps that are otherwise, and have previously been,required during re-painting or reworking a composite material substrateare obviated; resulting in a substantial reduction in resourcesincluding, for example, material cost for reworking and/or replacingUV/visible light-damaged layers, manpower hours previously required forindividual layer application treatment (e.g., individual layerpre-treatment surfacing steps, layer application steps, layerpost-treatment surfacing steps (including chemical application, physicalsurfacing treatments such as, including sanding, etc.), inspection ofdeposited layers, etc.).

According to present aspects, FIG. 2A shows an enlarged cross-sectionalrepresentative side view of a co-curable composite material assembly 20a consisting of a co-curable composite material substrate 22 a (having aco-curable composite material substrate first side 22 a′ and a compositematerial substrate second side 22 a″) with a co-curable UV/visiblelight-resistant layer 24 a disposed onto the co-curable compositematerial 22 a, (with the co-curable UV/visible light-resistant layer 24a having a co-curable UV/visible light-resistant layer first side 24 a′and a co-curable UV/visible light-resistant layer second side 24 a″).According to present aspects the co-curable composite assembly 20 a canbe co-cured to form a co-cured composite material assembly. Theco-curable composite material 20 a can be subjected to a co-curingregimen where the co-curable UV/visible light-resistant layer 24 adisposed onto the co-curable composite material substrate 22 a aretogether co-cured at a curing temperature less than 400° F., and morepreferably at a temperature ranging from about 250° F. to about 410° F.for a suitable duration to co-cure the two components to form a co-curedUV/visible light-resistant composite material assembly.

As shown in FIG. 2A, the co-curable composite material substrate 22 acan be a co-curable epoxy-resin-based composite material, and furthercan be a co-curable carbon fiber reinforced polymer composite materialsubstrate, with the composite material substrate assembly able to beused to form structural composite materials for the manufacture ofstructural components and structural component assemblies of vehiclesincluding, for example, the aircraft wing assembly fuel tank of the typerepresented, for example, in FIG. 1B, and that can be of the type offuel tank that can be installed into the vehicle shown in the form of anaircraft illustrated in FIG. 1A.

FIG. 2B shows a representative enlarged cross-sectional side view of aco-cured UV/visible light-resistant composite material assembly 20 bthat is formed from the uncured and co-curable components shown in FIG.2A, and that, in the cured state as shown in FIG. 2B, includes aco-cured UV/visible light-resistant layer 24 b (with the co-curableUV/visible light-resistant layer 24 a (having a co-curable UV/visiblelight-resistant layer first side 24 b′ and a co-curable UV/visiblelight-resistant layer second side 24 b″) that is co-cured with theco-cured composite material substrate 22 b (having a co-curablecomposite material substrate first side 22 b′ and a composite materialsubstrate second side 22 b″). According to present aspects, the co-curedUV/visible light-resistant layer 24 b can be a single ply, or can bemore than one ply, with the co-cured UV/visible light-resistant layer 24b able to exclusively impart (i.e., is essentially 100% responsible forimparting) a selected degree of UV/visible light protection to theunderlying co-cured composite material substrate 22 b such that theco-cured UV/visible light-resistant layer has a UV/visible lighttransmittance value ranging from about 0% to about 20% UV/visible lighttransmittance for UV/visible wavelengths ranging from about 200 nm toabout 800 nm when the co-cured UV/visible light-resistant layercomprises an average thickness ranging from about 2 mils to about 6 mils

According to present aspects, the co-cured UV/visible light-resistantcomposite material assembly 20 b, as shown in FIG. 2B, can be used as astructural component that includes an interior surface of, for example,an aircraft wing assembly fuel tank. When the presently disclosedcomposite materials are used to form an interior structure (e.g., a fueltank cavity, etc.) during formation of the composite material substrate,it is understood that an inner mold line (IML) 25 a, 25 b can betransferred to the co-curable and the co-cured composite materialsubstrate from, for example, a composite material forming tool orforming surface (e.g., a mandrel, etc.). Such inner mold line istransferred to and otherwise present on the co-cured UV/visiblelight-resistant layer 24 b, with the IML located on the interior surfaceof a structure, such as, for example, the wing assembly fuel tank innersurface 13 b of the aircraft wing assembly 13 as shown, for example, inFIG. 1B.

According to present aspects, the UV/visible light-resistant layer isselected to have a UV/visible light resistance characteristic and valuesuch that the co-cured UV/visible light-resistant layer alone is solelyresponsible for imparting the selected degree of UV/visiblelight-resistance and UV/visible light protection to the underlying epoxyresin-based composite material. That is, according to present aspects,the UV/visible light blocking capabilities of the presently disclosedco-cured UV/visible light-resistant layer eliminate the need for, renderredundant, and otherwise obviate the presence of any additionalUV/visible light-resistant layer in the presently disclosed compositematerial systems, as well as obviating the need for incorporatingUV/visible light blocking agents into the composite material substrate.Instead, the entire UV/visible light-blocking function for the presentlydisclosed co-cured composite material assemblies, and structuresincorporating the presently disclosed co-cured composite materialassemblies, is completely satisfied by the UV/visible light-blockingcapabilities introduced to the resulting cured composite materialassembly by the UV/visible light-resistant layer, that can be, forexample, a single ply UV/visible light-resistant layer. Such redundant,obviated, and/or eliminated layer(s) include, for example, UV/visiblelight-resistant paints, UV/visible light-resistant primers, UV/visiblelight-resistant topcoats. Again, according to present aspects, noadditional UV/visible light-resistant layers are present in thedisclosed co-cured composite materials or are needed to achieve thedesired and selected UV/visible light-blocking function present withinthe presently disclosed co-cured composite material assemblies.

According to present aspects, as shown in FIG. 2B, the co-curedcomposite material substrate 22 a can be a co-cured epoxy-resin-basedcomposite material, and further can be a co-cured carbon fiberreinforced polymer composite material substrate, with the co-curedcomposite material substrate assembly configured to form structuralcomposite materials for the manufacture of structural components andstructural component assemblies of vehicles including, for example, theaircraft wing assembly fuel tanks of the type represented, for example,in FIG. 1B, and that can be of the type of fuel tank that can beinstalled into the vehicle shown in the form of an aircraft illustratedin FIG. 1A.

According to present aspects, when configured as various aircraftstructural composite materials, the co-cured UV/visible light-resistantcomposite material assemblies 20 b of the type shown in FIG. 2B can beconfigured to accept and otherwise facilitate the deposition of variousprimer and topcoat layers that can either become a part of, or precedethe formation of an interior of a vehicle fuel tank such as, forexample, the interior (e.g., the interior cavity wall or cavityboundary, etc.) of a large structural assembly such as, for example, avehicle fuel tank that can be, for example, an aircraft wing assemblyfuel tank of the type shown in FIG. 1B, with the aircraft wing assemblyfuel tank of the type that can be installed to reside within theaircraft wing assembly of the aircraft as shown in FIG. 1A.

FIG. 2C is an enlarged cross-sectional representative side view of aco-cured UV/visible light-resistant composite material assembly 20 c inthe form of a co-cured composite material system that further includesthe co-cured UV/visible light-resistant composite material assemblylayers shown in FIG. 2B (as assembly 20 b). That is, FIG. 2C shows aco-cured composite material substrate 22 c with the co-cured UV/visiblelight-resistant layer 24 c applied and disposed onto the co-cured epoxyresin composite material substrate 22 c. As further shown in FIG. 2C,and according to present aspects, the co-cured UV/visiblelight-resistant composite material assembly does not contain any furtherUV/visible light-resistant material (e.g., in the form of UV/visiblelight-resistant primer layer(s) or UV/visible light-resistant paintlayer(s), etc.). That is, as shown in FIG. 2C, and according to presentaspects, the UV/visible light-resistant layer 24 c is solely responsiblefor imparting UV/visible light-resistance to the UV/visiblelight-resistant composite material assembly 20 c (e.g., inhibitingUV/visible light radiation from passing through the co-cured UV/visiblelight-resistant layer to the underlying co-cured composite materialsubstrate). As shown in FIGS. 2B and 2C, the co-cured composite materialsubstrate can be a co-cured carbon fiber reinforced polymer compositematerial substrate and can further be a co-cured epoxy resin-basedcomposite material substrate.

The co-cured UV/visible light-resistant composite material assembly 20 cas shown in FIG. 2C further comprises a fuel tank primer layer 26 c,covering the co-cured UV/visible light-resistant layer 24 c. Accordingto present aspects, the average thickness of the fuel tank primer, ifdesired, can be greatly reduced from the amount and layer thickness ofconventional fuel tank primer layers previously required for knowncomposite material assemblies. More specifically, the present co-curedUV/visible light-resistant composite material assemblies comprising theUV/visible light-resistant layer can facilitate reducing the thicknessof, or eliminating the need for a fuel tank primer layer. Such reductionin thickness (equivalently referred to herein as “primer coating layerthickness”), or elimination of the fuel tank primer can result in asignificant weight reduction, cost reduction, processing time reduction,rework time reduction, man/hour labor reduction, and required materialreduction due to the scale of a large structure having large structureassemblies including, for example, an aircraft wing assembly fuel tank.

Further present aspects contemplate co-curable composite materials andco-cured composite materials, assemblies comprising the co-curedcomposite materials, sub-assemblies comprising the co-cured compositematerials, and structures comprising at least one of the assembliesand/or sub-assemblies comprising the co-cured UV/visible light-resistantcomposite materials that are made according to the methods set forthherein, including, for example, crewed aircraft, an uncrewed aircraft, acrewed spacecraft, an uncrewed spacecraft, a crewed rotorcraft, anuncrewed rotorcraft, a crewed terrestrial vehicle, an uncrewedterrestrial vehicle, a crewed surface water borne vehicle, an uncrewedwaterborne vehicle, a crewed sub-surface water borne vehicle, anuncrewed sub-surface water borne vehicle, a satellite, and combinationsthereof.

FIGS. 3 and 4 are flowcharts outlining methods for making the presentlydisclosed co-curable and co-cured composite materials. As shown in FIG.3 , method 100 is outlined, with method 100 comprising providing 102 aco-curable composite material substrate that can be a co-curable epoxyresin-based fiber reinforced composite material substrate, and canfurther be a co-curable carbon fiber reinforced polymer materialsubstrate. Method 100 further comprises positioning 104 a co-curableUV/visible light-resistant layer onto the co-curable composite materiallayer, with the composite material substrate having an inner mold line.The composite material substrate can be a co-curable epoxy resin-basedcomposite substrate material and can further be a carbon fiberreinforced polymer composite material. The co-curable UV/visiblelight-resistant layer comprises at least one of fiberglass fibers,carbon fibers, polyester fibers, aramid fibers, boron fibers, quartz,and combinations thereof. According to present aspects, the co-curableUV/visible light-resistant layer can be a single layer ply, or can be aplurality of layer plies such that the co-curable UV/visiblelight-resistant layer has a UV/visible light transmittance value rangingfrom about 0% to about 20% UV/visible light transmittance for UV/visiblewavelengths ranging from about 200 nm to about 800 nm when theUV/visible light-resistant layer comprises an average thickness rangingfrom about 2 mils to about 6 mils. The co-curable UV/visiblelight-resistant composite material assembly comprising the co-curableUV/visible light-resistant layer can be of the type shown and describedat least in FIG. 2A and described herein. Method 100 further comprisesco-curing 106 the co-curable composite material substrate with theco-curable UV- resistant layer at a temperature ranging from about 250°F. to about 410° F. to form a co-cured UV/visible light-resistantcomposite material fuel tank assembly of the type shown in FIG. 1B andfurther described herein. Method 100 further contemplates the formationof a co-cured UV/visible light-resistant composite material assembly ofthe type shown and described at least in FIGS. 2B and 2C and describedherein.

FIG. 4 is a flowchart outlining a method, according to present aspects.As shown in FIG. 4 , method 200 comprises providing 102 a co-curablecomposite material substrate that can be a co-curable epoxy resin-basedfiber reinforced composite material substrate, and that can further be aco-curable carbon fiber reinforced polymer material substrate. Method200 further comprises applying and positioning 104 a co-curableUV/visible light-resistant layer comprising at least one of fiberglassfibers, carbon fibers, polyester fibers, aramid fibers, boron fibers,quartz, and combinations thereof, onto the co-curable composite materiallayer, with the composite material substrate having an inner mold line.According to present aspects, the co-curable UV/visible light-resistantlayer can be a single ply, and can be a single ply or a plurality ofplies such that the co-curable UV/visible light-resistant layer has aUV/visible light transmittance value ranging from about 0% to about 20%UV/visible light transmittance for UV/visible wavelengths ranging fromabout 200 nm to about 800 nm when the UV/visible light-resistant layercomprises an average thickness ranging from about 2 mils to about 6mils. The co-curable UV/visible light-resistant composite materialassembly comprising the UV/visible light-resistant layer can be of thetype shown and described at least in FIG. 2A, and further describedherein. Method 200 further comprises co-curing 106 the co-curablecomposite material layer with the co-curable UV- resistant layer at atemperature ranging from about 250° F. to about 410° F. to form aco-cured UV/visible light-resistant composite material fuel tankassembly of the type shown in FIG. 1B and further described herein.Method 200, according to present aspects, further comprises providing108 a fuel tank primer to the co-cured UV/visible light-resistant layerto form, for example, a co-cured composite material assembly of the typeshown in FIG. 2C, with the co-cured composite material assemblyconfigured to form the aircraft wing assembly fuel tank of the typeshown, for example, in FIG. 1B.

The present aspects may, of course, be carried out in other ways thanthose specifically set forth herein without departing from essentialcharacteristics of the present disclosure. The present aspects are to beconsidered in all respects as illustrative and not restrictive, and allchanges coming within the meaning and equivalency range of the appendedclaims are intended to be embraced therein.

What is claimed is:
 1. A co-curable composite material comprising: aco-curable composite material substrate; a co-curable UV/visiblelight-resistant coating layer, said co-curable UV/visiblelight-resistant coating layer in direct contact with said co-curablecomposite material substrate to form a co-curable UV/visiblelight-resistant layer-coated composite material substrate assembly, saidco-curable UV/visible light-resistant coating layer comprising at leastone of fiberglass fibers, carbon fibers, polyester fibers, aramidfibers, boron fibers, quartz, and combinations thereof, said co-curableUV/visible light-resistant layer-coated composite material substrateassembly configured to form a vehicle fuel tank, said vehicle fuel tankcomprising: a vehicle fuel tank inner surface; a vehicle fuel tankcavity, said vehicle fuel tank cavity defined by the vehicle fuel tankinner surface, said vehicle fuel tank inner surface exclusivelycomprising the co-curable UV/visible light-resistant coating layer;wherein said co-curable UV/visible light-resistant coating layer has aUV/visible light transmittance value of 0% to about 20% for UV/visiblelight wavelengths ranging from about 200 nm to about 800 nm when theco-curable UV/visible light-resistant coating layer comprises an averagethickness ranging from about 2 mils to about 6 mils; and wherein saidco-curable UV/visible light-resistant coating layer is configured tocompletely cover said co-curable composite material substrate.
 2. Theco-curable composite material of claim 1, wherein the co-curablecomposite material substrate is co-curable with the co-curableUV/visible light-resistant coating layer at a temperature ranging fromabout 250° F. to about 410° F.
 3. The co-curable composite material ofclaim 1, wherein the co-curable composite material substrate comprisesan epoxy resin-based matrix.
 4. The co-curable composite material ofclaim 1, wherein the co-curable composite material substrate comprises afiber reinforced epoxy resin-based matrix comprising at least one ofcarbon fibers, boron fibers, aramid fibers, fiberglass fibers, polyesterfibers, and combinations thereof.
 5. The co-curable composite materialof claim 1, wherein the co-curable composite material substratecomprises a carbon fiber reinforced polymer composite material.
 6. Theco-curable composite material of claim 1, wherein the co-curablecomposite material substrate comprises at least one carbon fiberreinforced polymer prepreg.
 7. A vehicle fuel tank comprising: a vehiclefuel tank assembly comprising a co-cured composite material, saidvehicle fuel tank assembly comprising a vehicle fuel tank inner surface,said vehicle fuel tank inner surface comprising: a co-cured compositematerial substrate; a co-cured UV/visible light-resistant layer, saidco-cured UV/visible light-resistant coating layer comprising at leastone of fiberglass fibers, carbon fibers, polyester fibers, aramidfibers, boron fibers, quartz, and combinations thereof, said co-curedUV/visible light-resistant layer in direct contact with the co-curedcomposite material substrate, said co-cured UV/visible light-resistantlayer configured to completely cover the co-cured composite materialsubstrate; a vehicle fuel tank cavity, said vehicle fuel tank cavitydefined by the vehicle fuel tank inner surface; wherein the co-curedcomposite material substrate and the co-cured UV-resistant layer areco-cured in a co-curing regimen to form the co-cured vehicle fuel tankassembly, said co-curing regimen comprising a co-curing temperatureranging from about 250° F. to about 410° F.; and wherein the co-curedUV/visible light-resistant layer has a UV/visible light transmittancevalue of 0% to about 20% for UV/visible light wavelengths ranging fromabout 200 nm to about 800 nm when the co-cured UV/visiblelight-resistant layer comprises an average thickness ranging from about2 mils to about 6 mils.
 8. The vehicle fuel tank of claim 7, wherein theco-cured composite material substrate comprises an epoxy resin-basedmatrix.
 9. The vehicle fuel tank of claim 7, wherein the co-curedcomposite material substrate comprises a fiber reinforced epoxyresin-based matrix comprising at least one of carbon fibers, boronfibers, aramid fibers, fiberglass fibers, polyester fibers, andcombinations thereof.
 10. The vehicle fuel tank of claim 7, wherein theco-cured composite material substrate comprises a carbon fiberreinforced polymer composite material.
 11. The vehicle fuel tank ofclaim 7, wherein the co-cured composite material substrate comprises atleast one carbon fiber reinforced polymer prepreg.
 12. The vehicle fueltank of claim 7, wherein the co-cured UV/visible light-resistant layeris configured to form the vehicle fuel tank inner surface.
 13. Thevehicle fuel tank of claim 7, further comprising a fuel tank primerlayer (26c) disposed to cover the co-cured UV/visible light-resistantlayer, said vehicle fuel tank inner surface defined by the fuel tankprimer layer.
 14. The vehicle fuel tank of claim 7, wherein inclusion ofthe said co-cured UV/visible light-resistant layer in the co-curedvehicle fuel tank assembly obviates the presence of at least one of afuel tank primer layer and a UV-absorbing paint layer in the vehiclefuel tank assembly.
 15. An aircraft wing assembly comprising the vehiclefuel tank of claim
 7. 16. A vehicle comprising the vehicle fuel tank ofclaim
 7. 17. The vehicle of claim 16, wherein the vehicle is selectedfrom the group consisting of: a crewed aircraft, an uncrewed aircraft, acrewed spacecraft, an uncrewed spacecraft, a crewed rotorcraft, anuncrewed rotorcraft, a crewed terrestrial vehicle, an uncrewedterrestrial vehicle; a crewed surface water borne vehicle, an uncrewedwaterborne vehicle, a crewed sub-surface water borne vehicle, anuncrewed sub-surface water borne vehicle, a satellite, and combinationsthereof.
 18. A method comprising: providing a co-curable compositematerial substrate, said co-curable composite material substratecomprising a co-curable composite material substrate first side and aco-curable composite material substrate second side; applying aco-curable UV/visible light-resistant layer onto said co-curablecomposite material substrate second side, said co-curable UV/visiblelight-resistant coating layer comprising at least one of fiberglassfibers, carbon fibers, polyester fibers, aramid fibers, boron fibers,quartz, and combinations thereof, said co-curable UV/visiblelight-resistant layer applied onto the co-curable composite materialsubstrate second side at an average thickness ranging from about 2 milsto about 6 mils; and co-curing the co-curable composite materialsubstrate with the co-curable UV/visible light-resistant layer to form aco-cured composite material vehicle fuel tank assembly, said co-curedcomposite material vehicle fuel tank assembly comprising a co-curedvehicle fuel tank assembly inner surface, said co-cured vehicle fueltank assembly inner surface consisting of a co-cured UV/visiblelight-resistant layer having a UV/visible light transmittance value of0% to about 20% for UV/visible light wavelengths ranging from about 200nm to about 800 nm when the co-cured UV/visible light-resistant layercomprises an average thickness ranging from about 2 mils to about 6mils, said co-cured UV/visible light-resistant layer configured todefine a vehicle fuel tank cavity; and wherein inclusion of the co-curedUV/visible light-resistant layer in the co-cured composite materialvehicle fuel tank assembly obviates the need for the presence of atleast one of a UV/visible light-absorbing detail primer layer and aUV/visible light-absorbing paint layer in the co-cured compositematerial vehicle fuel tank assembly.
 19. The method of claim 18 whereinthe co-curable composite material substrate comprises a fiber reinforcedepoxy resin-based matrix comprising at least one of carbon fibers, boronfibers, aramid fibers, fiberglass fibers, polyester fibers, andcombinations thereof.
 20. The method of claim 18, wherein the co-curablecomposite material substrate comprises a carbon fiber reinforced polymercomposite material.
 21. The method of claim 18, further comprisingapplying a fuel tank primer layer on the co-cured UV/visiblelight-resistant layer.